Dentosphere : World of Dentistry

 # Stainless steel wire can be hardened by: A. Tempering B. Work hardening C. Annealing D. Pulse straightening The correct answer is B. Work hardening. Cold Working (Strain Hardening/Work Hardening): It is the process of plastically deforming metal at a temperature, lower than at which it recrystallizes new grains. This temperature is usually one-third to one-half of its absolute melting point. Cold working disrupts the regular atomic arrangement and incorporates strain across the grain boundaries.  Annealing: It is the process of reversing the effects of cold working. In a clinical setting, a wire is considered annealed when it appears red hot. Hysteresis: The difference between the energy required to activate the wire by deflection and that it releases during deactivation. This is called energy loss or hysteresis.  Heat treatment: It refers to a general process of using thermal energy to change the characteristics of metallic alloys as tempering, precipitation hardening...

 # Which of the following craniofacial syndromes is not associated with craniosynostosis? A. Apert syndrome B. Crouzon syndrome C. Pfeiffer syndrome D. Treacher Collins syndrome The correct answer is D. Treacher Collins syndrome. Craniosynostosis is a condition in which one or more of the fibrous sutures in a young infant's skull prematurely fuses by turning into bone (ossification), thereby changing the skull's growth pattern. Because the skull cannot expand perpendicular to the fused suture, it compensates by growing more in the direction parallel to the closed sutures. Sometimes the resulting growth pattern provides the necessary space for the growing brain but results in an abnormal head shape and abnormal facial features. In cases in which the compensation does not effectively provide enough space for the growing brain, craniosynostosis results in increased intracranial pressure leading possibly to visual impairment, sleeping impairment, eating difficulties, or an impairme...

 # Most damaging feature of class III malocclusion is: A. Retroclined upper anterior teeth B. Crowding of lower incisors C. Deviated path of closure D. Reduced overbite The correct answer is D. Reduced overbite. Deep bite is the most damaging feature of class II malocclusion. Reduced deep bite is the most damaging feature of class III malocclusion.

 # Most common site for melanotic neuroectodermal tumour of infancy (MNTI) is: A. Maxilla B. Mandible C. Ethmoid bone D. Cervical spine The correct answer is A. Maxilla. MNTI is an uncommon osteolytic, pigmented neoplasm, primarily affecting the jaws of new born infant. Its origin is linked to neural crest cells. More than 90% occur in the head and neck region especially the anterior part of the maxillary ridge. They appear as rapidly growing, non-ulcerated, darkly pigmented lesions, with a radiographic appearance of an invasive malignant neoplasm. 

 # Dimensions of inner bow of facebow are: A. 0.045’’ and 1.125 mm B. 0.06’’ and 0.09’’ C. 0.045’’ and 1.25 mm D. 0.45’’ and 0.71’’ The correct answer is A. 0.045’’ and 1.125 mm Face bow and 'J' hook are force delivering units of a head gear. The face bow helps in delivering extra oral force to the posterior teeth. It consists of outer bow or whisker bow, inner bow, junction, force generating unit and anchor unit.  Outer bow:   • It is made of round stainless steel wire 0.051 or 0.062 inch.  • It is contoured around the face  • It may be short, medium or long in relation to inner bow.  Inner bow:  • It is made of 0.045 inch (1.125 mm) or 0.052 inch (1.3 mm) round stainless steel wire.  • Inserts into the round buccal tube on the maxillary first molars. 

 Thesis and research is a part of MDS curriculum. Here are some good research topics to consider if you are an MDS Orthodontics Resident. Assessment of the relationship between maxillary and mandibular incisors in Class I, Class II, and Class III malocclusions Evaluation of the effectiveness of different treatment modalities for correcting Class II malocclusion in growing patients Comparison of the effectiveness of fixed and removable functional appliances in correcting Class II malocclusion

 # Hemifacial microsomia is a feature of: A. Goldenhar syndrome B. Crouzon syndrome C. Treacher Collins syndrome D. Mandibulofacial dysostosis The correct answer is A. Goldenhar syndrome. Hemifacial microsomia is a feature of Goldenhar syndrome. Synonyms for hemifacial microsomia include hemifacial hypoplasia, craniofacial microsomia, lateral facial dysplasia, Goldenhar syndrome, and oculoauriculovertebral dysplasia (OAV) spectrum.  B is incorrect; Hemifacial microsomia is not a feature of Crouzon syndrome. Patients with Crouzon syndrome characteristically have brachycephaly (short skull front to back), hypertelorism (increased distance between eyes), and orbital proptosis (protruding eyes).  C is incorrect; Hemifacial microsomia is not a feature of Treacher Collins syndrome. The most common clinical findings in Treacher Collins syndrome are relative underdevelopment or absence of the zygomatic bones, resulting in a small narrow face; a downward inclination of the palpebr...

 # The gene aberrant in dentinogenesis imperfecta is: A. Chromosome 4 B. Chromosome 13 C. Chromosome 21 D. Chromosome 24 The correct answer is A. Chromosome 4. Aberration in chromosome 4 (4q21.3) is associated with Dentinogenesis imperfecta. It encodes dentin specific sialophosphoprotein (DSPP) gene. Deficiency of sialoprotein is also suggested as a causative factor for DI. They are generally tulip shaped.  Chromosome number              Disease  1                                               Vanderwoude syndrome 4                                               Dentinogenesis Imperfecta  4                              ...

 # Deficiency of which vitamin causes glossitis, dementia, rough keratotic areas on skin and gastrointestinal symptoms? A. Riboflavin B. Pyridoxine C. Niacin D. Pantothenic acid The correct answer is C. Niacin. Pellagra is a disease caused by a lack of the vitamin niacin (vitamin B3). Symptoms include inflamed skin, diarrhea, dementia, and sores in the mouth. Areas of the skin exposed to either sunlight or friction are typically affected first. Over time affected skin may become darker, stiffen, peel, or bleed. There are two main types of pellagra, primary and secondary. Primary pellagra is due to a diet that does not contain enough niacin and tryptophan. Secondary pellagra is due to a poor ability to use the niacin within the diet. This can occur as a result of alcoholism, long-term diarrhea, carcinoid syndrome, Hartnup disease, and a number of medications such as isoniazid. Diagnosis is typically based on symptoms and may be assisted by urine testing. 

 # FIGLU excretion test is used to estimate deficiency of: A. Vitamin K B. Vitamin B12 C. Vitamin Folic acid D. Niacin The correct answer is C. Vitamin Folic acid. Folic acid is associated with the metabolism of histidine. Formiminoglutamate (FIGLU) formed in histidine metabolism accumulates and is excreted in urine. Histidine load test utilizing the excretion of FIGLU in urine is used to assess folic acid deficiency. 

 # Which of the following vitamins is destroyed by heat? A. Vitamin A B. Vitamin D C. Biotin D. Thiamin The correct answer is C. Biotin. Biotin is present in many foods, including liver, grains, and eggs. It is also synthesized by intestinal bacteria. The conversion to a coenzyme simply requires that it be covalently linked to the appropriate enzymes. Biotin acts as a carrier of "activated carboxyl" groups for three key enzymes that catalyze carboxylation reactions. The enzymes and the pathways they participate in are: Pyruvate carboxylase (gluconeogenesis), acetyl-CoA carboxylase (fatty acid synthesis), and propionyl-CoA carboxylase (branched chain amino acid catabolism). Biotin deficiency is rare. Excessive consumption of raw egg impairs biotin absorption due to the presence of a biotin-binding protein, avidin, in egg whites. Antibiotics that alter the intestinal flora can also lead to biotin deficiency. Symptoms of deficiency include alopecia, skin and bowel inflammation, ...

# All of the cranial nerve have parasympathetic outflow EXCEPT: A. 5th Nerve B. 7th Nerve C. 3rd Nerve D. 9th Nerve # The future TMJ shows development at: A. 12 week B. 10 week C. 18 week D. 16 week # Area that lies immediately lateral to the anterior perforating substance is: A. Orbital gyrus B. Uncus C. Optic chiasma D. Limen insulae   # Which of the following organ is located posterior to pancreas? A. Kidney B. Stomach C. Colon D. Duodenum # Intrinsic factor of Castle is secreted by which of the following cells in Gastric glands? A. Chief cells B. Parietal cells C. Mucus cells D. B cells # A patient was diagnosed with isolated increase in LDL. His father and brother had the same disease with increased cholesterol. The likely diagnosis is: A. LDL receptor mutation B. Familial lipoprotein lipase deficiency type I C. Familial type 3 hyperlipo...

 # During a Le fort I maxillary osteotomy, the tooth most likely to be injured by a low osteotomy line is the: A. Central incisor B. Cuspid C. First bicuspid D. Lateral incisor The correct answer is B. Cuspid. The cuspids, or canine teeth, have the longest roots in both the maxilla and mandible. The average length of a cuspid tooth from the tip of the root to the tip of the crown is 27 mm. It is vital to know the length and position of the dental roots to avoid injuring the apices of the cuspid teeth during Le Fort I osteotomy and placement of internal fixation (interosseous miniplates or microplates and screws). The dentition may also be injured during stabilization of maxillary or mandibular fractures. The bicuspid, central and lateral incisor, and molar teeth all have roots that are shorter than the roots of the cuspid teeth; the average length of a molar tooth from the tip of the root to the tip of the crown, for example, is 24 mm. Consequently, these teeth are much less likely...

 # Bupivacaine is known to cause rapid and resistant cardiac toxicity when administered in high concentrations and volumes. What is the recent advancement to treat its cardiac toxicity? A. Buffered local anesthetics B. Addition of mannitol to local anesthetic solution C. Use of lipid emulsions to reverse the cardiotoxicity of local anesthetics D. Addition of another anesthetic to bupivacaine The correct answer is C. Use of lipid emulsions to reverse the cardiotoxicity of local anesthetics. Cardiovascular collapse from accidental local anesthetic toxicity is rare but the long-acting amide local anesthetics bupivacaine, levobupivacaine, and ropivacaine have differential cardiac toxicity, but all are capable of causing death with accidental overdose. In recent times, the discovery that lipid emulsion may improve the chance of successful resuscitation has led to recommendations that it should be available in every location where regional anesthesia is performed. 

 # Best method of intubation in patient undergoing treatment for oral surgery under GA is: A. LMA B. Orotacheal tube C. Laryngeal mask airway D. Naso-endotube The correct answer is D. Naso-endotube. Solution:  The sine qua non for intubation since the twentieth for general anesthesia patients is pharyngeal laryngoscopy and oral intubation. But here the question is about oral surgery treatment. In such cases, nasal intubation is often preferred in patients for unrestricted direct access to the mouth and pharynx regions.  In cases where the direct intubation cannot be done, blind methods such as combitube, LMA can be used. They however interfere with oral surgical procedures.  If the question is asked about maxillofacial injuries in general then the answer is oral intubation. If the question is about oral surgical procedures, the answer is nasal intubation. 

 # Which of the following is not a feature of torus mandibularis? A. Common in mongoloids B. Present on the lingual surface of mandible below the mylohyoid line C. Usually bilateral D. May or may not be associated with torus palatinus The correct answer is B. Present on the lingual surface of mandible below the mylohyoid line. The torus mandibularis is an exostosis or outgrowth of bone found on the lingual surface of the mandible. This growth on the lingual surface of the mandible occurs above the mylohyoid line, usually opposite the bicuspid teeth. Although the mandibular tori are usually bilateral, they are seen as a unilateral condition in about 20% of the cases. Both unilateral and bilateral protuberances may be single or multiple, and they are frequently visible on dental periapical radiographs. There is no correlation in the frequency of simultaneous occurrence of torus palatinus and torus mandibularis, according to the studies of Kolas and coworkers, suggesting that the two ...

 # Gardner syndrome does not include: A. Osteomas B. Epidermoid cysts C. Osteosarcoma D. Impacted permanent teeth The correct answer is C. Osteosarcoma. Gardner syndrome is also characterized by the occurrence of multiple impacted supernumerary teeth. This syndrome consists of:  1. multiple polyposis of the large intestine, 2. Osteomas of the bones, including long bones, skull, and jaws, 3. Multiple epidermoid or sebaceous cysts of the skin, particularly on the scalp and back, 4. Occasional occurrence of desmoid tumors, and 5. Impacted supernumerary and permanent teeth  Osteosarcoma is not a feature of Gardner Syndrome.

 # The most important diagnostic test to differentiate between an acute periapical abscess and a phoenix abscess is:  a) Pulp testing b) Radiographs c) History d) Percussion The correct answer is B. Radiographs. Phoenix abscess is an acute inflammatory reaction superimposed on an existing chronic lesion, such as a cyst or granuloma. The exacerbation of a chronic lesion is most commonly associated with the initiation of root canal therapy in a completely asymptomatic tooth. In such a tooth, radiographs show well-defined periradicular lesions.

 # The deciduous tooth which does not have a resemblance to any other teeth is: a) Maxillary first molar  b) Mandibular first molar c) Maxillary 2nd molar  d) Mandibular canine The correct answer is B. Mandibular first molar. The deciduous mandibular first molar is unique in that it has a crown form unlike that of any permanent tooth. It does, however, have two strong roots, one mesial and one distal—an arrangement similar to that of a mandibular permanent molar. These two primary teeth, the maxillary and mandibular first molars, differ from any teeth in the permanent set when crown forms are compared, in particular.

 # The microorganism most commonly cultured from a chronic bilateral ulcer at the corner of the mouth: a) Mucor  b) Candida c) Treponema  d) Aspergillus The correct answer is B. Candida.  Angular cheilitis (AC) is inflammation of one or both corners of the mouth. Often the corners are red with skin breakdown and crusting. It can also be itchy or painful. The condition can last for days to years. Angular cheilitis is a type of cheilitis (inflammation of the lips). Angular cheilitis can be caused by infection, irritation, or allergies. Infections include fungi such as Candida albicans and bacteria such as Staph. aureus. Irritants include poorly fitting dentures, licking the lips or drooling, mouth breathing resulting in a dry mouth, sun exposure, overclosure of the mouth, smoking, and minor trauma. Allergies may include substances like toothpaste, makeup, and food. Often a number of factors are involved. Other factors may include poor nutrition or poor immune function....

 # Phlegmon is a: a) Sexually transmitted disease b) Type of cellulitis c) Type of osteomyelitis  d) Venereal disease The correct answer is B. Type of  cellulitis. Cellulitis or Phlegmon is a diffuse inflammation of soft tissues that\ is not circumscribed or confined to one area, but which, contrary to the abscess, tends to spread through tissue spaces and along fascial planes. This type of reaction occurs due to infection by microorganisms that produce significant amounts of streptokinase, hyaluronidase (the spreading factor of Duran-Reynolds) and fibrinolysins, which act to breakdown or dissolve hyaluronic acid, the universal intercellular cement substance, and fibrin. Streptococci are particularly potent producers of hyaluronidase and are therefore a common causative organism in cases of cellulitis. Streptococci in their growth phase consume local oxygen and metabolize nutrients to produce an acidic environment, which is conducive to the subsequent growth of anaerobic ...